P1259 Accord '99 - please help!

Hey guys,
having problems with my car last few weeks...

What happened is had to replace the engine (2.3L VTEC 4cyl) due to one cylinder being damaged (CEL was flashing when I was driving on a highway). Not sure why, when I checked the oil after it was bellow minimum but not long before this it had good level. My mechanic said need to replace engine which I did with an imported one from Japan (I'm in Canada).

Now the car runs good but what's happening is as soon as I get on the highway CEL turns on with 'P1259 - Manufacturer Controlled Fuel and Air Metering'. When I clear it it comes back on the next time I get on the highway. Had the mechanic change Idle sensor, two temp sensors and EGR valve and still the same problem. After the CEL comes on my Idle speed does fluctuate from time to time when I stop.

Did anyone experience the same kind of issue?

Thanks guys!

You replaced an engine b/c you got a CEL and didnt' bother to diagnose it?
 
 
I think your code is the vtec malfunction code. Try changing the oil.

P1259 V-Tec oil pressure switch / V-Tec system malfunction.
First check oil level.
The pressure switch should have continuity with the engine off, and no continuity with engine running.
Opposite of what you would think huh?  LOL
 
I'm not the kind of person to make war on brothers in arms; But your mechanic is not very competent. Mental Midget parts swapping ripoff.
The EGR has nothing to do with the code, nor does it operate during idle RPMs
There is no such animal as an "Idle Sensor".
I'd say to check that there is slack in the throttle cable first when looking for the idle surge problem.

The reason why I had to replace my engine is different, had 'P0304 - cylinder #4 misfire', engine was running on three cylinders only.
Did an oil/filter change yesterday, still having the same problems...CEL turns on with P1259 when I get on hwy, after this idle speed does kinda fluctuate from time to time (between 400-900 RPMs) when I stop.

LOL...
So VTEC oil pressure switch could be the problem? Tried to reach two pins on the switch itself and could not do it that way. Can I check the other end of connector/cable going from VTEC pressure switch (and if so where does it go)? I did check other things...VTEC solenoid (continuity, voltages, even cleaned it) and voltages going to oil pressure switch, that's all good.

My mistake, when I said 'Idle sensor' I meant to say Idle Air Control valve that was replaced.

Throttle cable, you mean cable going to Throttle Position Sensor?

THANKS SO MUCH GUYS FOR YOUR HELP, REALLY APPRECIATED!

There is a screen on the solenoid that can be plugged with crud.
Try this link;
http://img383.imageshack.us/my.php?image=12597yf.gif

quote:

ORIGINAL: ludwize

The reason why I had to replace my engine is different, had 'P0304 - cylinder #4 misfire', engine was running on three cylinders only.
Did an oil/filter change yesterday, still having the same problems...CEL turns on with P1259 when I get on hwy, after this idle speed does kinda fluctuate from time to time (between 400-900 RPMs) when I stop.

 
A misfire does not require replacing the engine. You are seriously getting ripped off by your mechanic or whoever is working on your car.

A misfire is a result of something, not the root cause.  If the mechanic found a really bad reason for the misfire (like a hole in the piston) there's an outside possibility that you DID need a new engine.  The mechanic probably knows more than he's telling you.
 
OTOH, the mechanic may have simply discovered that he can get you to pay for a new engine.  YMMV, & we can't say much for sure without knowing more.
 

It wasn't just the misfire code, one cylinder was not working for real. Tried it with another spark plug and made sure there are sparks coming from distributor wire but the cylinder was dead. There was no holes in the piston, at least from what I know.

My original mechanic who diagnosed that I have to replace the engine is trustworthy, the problem is he wanted to charge more than double what the other guy did (with imported Japanese engine) to get it replaced. So now, because it's under warranty I have to go back to 2nd guy, if I go back to my original mechanic he'll charge me and right now after all the expenses don't have much money to spend on the car.

So after I had the engine replaced two problems are happening
- CEL comes on with P1259 after getting on the hwy
- Idle speed fluctuates (this was the worst in the beginning where the car would even stall but after mechanic changed: 1. Idle Air Control Valve, 2. EGR valve, 3. temp sensors, now it goes between 400-900 RPMs)

Did check voltages and continuity on VTEC system components (all good), still need to check VTEC pressure switch. Can I check for continuity on the other end of connector/wire going to pressure switch (and where does that go)? Can't reach the pressure switch directly to measure that.
Also was reading something about Engine Mount Control Solenoid Valve, is this only for automatics (as I have manual transmission)? If it could be related to my case how do I check that?

Guys - really appreciate your replies! Let me know if there is anything else you'd need to know to give me an idea what could be wrong here.

One more thing guys, also read about EGR ports being clogged with carbon. Is this something I need to worry about in my case? See it's a hassle of reaching them for cleaning.

THX

The vacuum-operated engine mount is only used on automatic-tranny cars.  Was yours originally an auto before the engine swap?
 
There may be some differences in the sensors for JDM engines.  For example I thought the VTEC oil pressure switch was just a USDM thing.
 

I think mechanic found the problem...
He replaced VTEC sensor and it works fine now, no CEL when I get on the hwy and also Idle speed is stable now.

Thanks so much for your help, all the best!